This invention relates to a plastic case for holding a magnetic tape cassette, and more specifically to a cassette case characterized by a unique construction of the pivotal joints between the case body and the cover.
Generally, a case 1 for magnetic tape cassette, as shown in FIGS. 1 and 2, is made of a case body 2 and a cover 4. The two case members are pivotally joined by a pair of small pivots 8 protruding inwardly from the opposing end portions of two side walls 6 of the case body 2, and a pair of corresponding holes 12 formed in two side walls 10 of the cover 4 and in which the pivots are turnably fitted. Each time a tape cassette is put out of or into the case, the cover 4 is turned open and back to the closed position about the pair of pivots 8 as the fulcrums.
With such a conventional cassette case 1, as is obvious from FIGS. 1 and 2, it is common that the outer faces of the side walls 10 of the cover and the inner faces of the side walls 6 of the case body 2 are very close to each other, and the repeated opening and closing of the case tend to cause the side walls 10 of the cover to rub up against the side walls 6 of the case body, abrading the both faces to powder little by little. The resulting particles deposit on the tape cassette and the tape inside. This can cause dropouts and output variations, with consequent dropout errors, wow and flutter, and other drawbacks in practical usage of the magnetic tape.
The conventional case for magnetic tape cassette has another disadvantage. Its cover is turnable through an angle much larger than necessary, in the range from 250 to 300 degrees. Sometimes, therefore, the user attempting to take out the cassette from the case inadvertently opens the cover too wide, letting the cassette fall to be broken.
A principal object of the invention, therefore, is to provide a novel case for holding a magnetic tape cassette, whose case body and cover are protected against abrading a friction with each other at the time of opening and closing of the case, by the coaction of arcuate protuberances formed around the pivots on the case body and also around the pivot holes of the cover.
Another object of the invention is to provide a magnetic tape cassette case which is capable of storing the magnetic tape without impairing the tape quality by any particles which may otherwise be formed by abrasion of the case due to repeated opening and closing, and also capable of avoiding any danger of dropping the cassette out of the case because of the cover turning open to excess.